Light object evenly and have a transparent or solid background
In General

The ultimate purpose of every 3D render engine is to create 2D images of 3D objects in a way that they are recognizable as 3D objects. A main aspect of this is light - and therefore also shadows. 

Depending on how realistic the source images are and how exact your image recognition software should work, keep that in mind. 

Transparent Background

Guessing from your rendered image, I assume you are using cycles. To get a transparent background, just get rid of the object that generates the white plane(s), then go to "Properties Window - Render - Film" and mark the Checkbox for transparent background. 



Light Setup

If you use Cycles instead of Blender internal you can avoid hard shadows to a point where there are nearly no shadows at all. Because it handles light "more naturally", it's really simple to recreate a diffuse light setup similar to what you would use in a photo studio setup.

Instead of a common light source, you can use planes, assign a light-emitting material to them and turn off their ray visibility. This method gives you more "visible" control over your light sources.

Depending on the plane's size and the strength of the light your shadows will get stronger. If you add more than one plane you can get to a point where there is nearly no shadowing at all. 

Here's the result with one light-emiting plane:



The same scene with six light-emiting planes, that are placed in even distances around the object:



Remember to turn off the camera ray visibility for your light planes.



Here's the .blend that contains the setup.